Calm down; things aren't quite as black as you might think. The study is about wild coffee plants, while the stuff in our cups is brewed from their domesticated descendants. Still, wild losses leave cultivated crops genetically vulnerable to a host of enemies, which could ultimately lead to lower quality and higher prices for coffee consumers.

"Arabica's history is punctuated by problems with diseases, pests, and productivity problems—and growers have always gone back to the wild and used genetic diversity to address them," said Aaron Davis, head of RGB Kew's coffee research program.

There are only two main types of cultivated coffee, Arabica (which comes from the wild plant Coffea arabica) and Robusta (derived from Coffea canephora). But there are more than 125 species in the wild, with more still being discovered, said Davis, who has been researching coffee plants for 15 years.

"That's one of the things that really surprised me when I first started working with wild coffee," he said. "I mean, here's this immensely important crop, and we don't even know what all the species are yet! And among all those wild species, there are certainly useful genes."

Arabica's Shaky Future

Arabica is the backbone of the coffee industry, accounting for 70 percent of global production, according to the International Coffee Organization. But most of it can be traced back to a handful of plants taken from Ethiopia in the 17th and 18th centuries, Davis said, and its narrow gene pool makes it "very susceptible."

The prospects are "profoundly negative," the study concluded. Even in a best-case scenario, two-thirds of the suitable growing locations would disappear by 2080—and at worst, nearly 100 percent. And that's factoring in only climate change, not deforestation.

Davis and other researchers visited South Sudan's Boma Plateau in April, intending to assess the feasibility of coffee production there. Instead, they discovered wild Arabica plants in extremely poor health.

"After a week or so in those forests, we realized that our objective had changed: It became a rescue mission," Davis said.

The study recommends that specimens from the Boma Plateau should be preserved in seed banks as soon as possible, because the species could be extinct as soon as 2020.

Arabica typically grows in the upper zones of vegetation on tropical mountains, explained botanist Peter Raven, who was not involved in the study. Because such species are already living on the edges of ecosystems, the plants have nowhere to go when temperatures rise. (See "Plants 'Climbing' Mountains Due to Global Warming.")

"The kinds of cloud forest climates where Arabica is native are disappearing, and the plants and animals that occur in them are going to be among the most threatened on Earth," Raven said. "Most coffee production throughout the world will be in trouble as the climate shifts."

Previous studies have established that both wild and cultivated Arabica are very climate sensitive, thriving only within a very narrow range of temperatures, Davis noted.

"So even if you do some very simple sums, it doesn't take much to realize that there's an intrinsic threat to these species from accelerated climate change," he said. "The logical conclusion is that coffee production will be negatively impacted as well."

Taking Action

The purpose of the study isn't to scare people, Davis said, but rather to inspire action.

"We're trying to understand: What if we don't do anything—what will happen? And what can we do about it now?" Davis said. "If we're proactive, we can avoid a dire situation."

The study identifies several "core sites" where wild Arabica can likely survive until at least 2080, and recommends that these areas be targeted for conservation.

Conservation activities have helped other species avert extinction, Davis said, so he remains optimistic about the future of wild coffee. Raven, however, takes more of a cup-half-empty view. While the goal of preserving plant species in the wild is "laudable," he said, seed banking is extremely important even in areas where extinction is not yet imminent.

"Regardless of what measures are taken in nature, we can confidently, and sadly, expect the genetic diversity of those populations to go downhill steadily year after year," said Raven. "Seeds from the most genetically valuable species should be stored now, before it is too late."

Robusta—a hardier coffee domesticated in the 19th century in response to a leaf rust epidemic that decimated Arabica crops in Southeast Asia—is mostly used in stronger brews like espresso and Turkish coffee. It can grow at lower altitudes and higher temperatures, so it's somewhat better poised to cope with climate change.

But that doesn't mean most coffee drinkers would simply switch what's in their cup without sputtering, Davis said.

"I can guarantee that we will not all be happy just drinking Robusta," Davis said. "As the name suggests, it's quite strong. Most people don't like the taste, and it has up to twice as much caffeine as Arabica. It's simply not the same drink. If we lost Arabica, I think large segments of the coffee market would disappear."

Such a shift could cause a serious economic jolt: According to the International Coffee Organization, coffee is the second most traded global commodity after oil, and the industry employs about 26 million people.